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| author | Andy Lutomirski <luto@kernel.org> | 2017-02-22 18:36:16 +0300 |
|---|---|---|
| committer | Radim Krčmář <rkrcmar@redhat.com> | 2017-03-01 19:03:22 +0300 |
| commit | b7ceaec112aa35aa287325754d8c52b8304892cd (patch) | |
| tree | af5014f643adf8db9d82178bfb22f68062ed41c2 /arch/x86/include/asm/desc.h | |
| parent | e3736c3eb3a6f7c0966923b629c9f92b558aa9c7 (diff) | |
| download | linux-b7ceaec112aa35aa287325754d8c52b8304892cd.tar.xz | |
x86/asm: Tidy up TSS limit code
In an earlier version of the patch ("x86/kvm/vmx: Defer TR reload
after VM exit") that introduced TSS limit validity tracking, I
confused which helper was which. On reflection, the names I chose
sucked. Rename the helpers to make it more obvious what's going on
and add some comments.
While I'm at it, clear __tss_limit_invalid when force-reloading as
well as when contitionally reloading, since any TR reload fixes the
limit.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Diffstat (limited to 'arch/x86/include/asm/desc.h')
| -rw-r--r-- | arch/x86/include/asm/desc.h | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h index cb8f9149f6c8..1548ca92ad3f 100644 --- a/arch/x86/include/asm/desc.h +++ b/arch/x86/include/asm/desc.h @@ -205,6 +205,8 @@ static inline void native_load_tr_desc(void) asm volatile("ltr %w0"::"q" (GDT_ENTRY_TSS*8)); } +DECLARE_PER_CPU(bool, __tss_limit_invalid); + static inline void force_reload_TR(void) { struct desc_struct *d = get_cpu_gdt_table(smp_processor_id()); @@ -220,18 +222,20 @@ static inline void force_reload_TR(void) write_gdt_entry(d, GDT_ENTRY_TSS, &tss, DESC_TSS); load_TR_desc(); + this_cpu_write(__tss_limit_invalid, false); } -DECLARE_PER_CPU(bool, need_tr_refresh); - -static inline void refresh_TR(void) +/* + * Call this if you need the TSS limit to be correct, which should be the case + * if and only if you have TIF_IO_BITMAP set or you're switching to a task + * with TIF_IO_BITMAP set. + */ +static inline void refresh_tss_limit(void) { DEBUG_LOCKS_WARN_ON(preemptible()); - if (unlikely(this_cpu_read(need_tr_refresh))) { + if (unlikely(this_cpu_read(__tss_limit_invalid))) force_reload_TR(); - this_cpu_write(need_tr_refresh, false); - } } /* @@ -250,7 +254,7 @@ static inline void invalidate_tss_limit(void) if (unlikely(test_thread_flag(TIF_IO_BITMAP))) force_reload_TR(); else - this_cpu_write(need_tr_refresh, true); + this_cpu_write(__tss_limit_invalid, true); } static inline void native_load_gdt(const struct desc_ptr *dtr) |